Force of flight BYU skating device measures impact of jumps and landings
When a figure skater lands a jump, she lands with about five to eight timesher bodyweight in force. Those high magnitude forces are due tothe fact that she's moving really quickly. She's landing from a height. She doesn'thave time to absorb those forces through the body, sothat force just gets transmitted straight from the ice up through her lowerextremities up to the back. When we look at the high speed tutorial, we can see not only how is the body absorbingthe forces but also how the body works
to generate these forces. A skater may dobetween 50 and 60 jumps on a day where they're preparing forcompetition. A lot of skaters by the time they're 20, 30, 40, have doublehip replacements from all the pounding and the damaged. You just feelold really young. They have a lot of force that they're landing with over and over again and this contributesto overuse injuries. So we've been designing a device that we can attached to a figure skate. It'll be unobtrusive to the skater, and it will measure the impact forces on takeoff and landing.
This is really the first time thatactual forces are measured on ice. In the lab testing, we've been having a skater jump onto aforce plate. This is really set up to get some baseline data initially. Wer'e collecting data from threedifferent spots: in the front, in the middle, and on the back part of the skate, and that's what the six different linesare we see on the screen. Right here where the large lines are is where she actually impacts.
So we want to be able to measure forces as small as six pounds and as great as a thousand pounds. When someone jumps on the ice, those tensions compress about one millionth of an inch. That's about one thousandth of the width a human hair. So very, very small compressions. It's a whole body workout. You can see just how much strength it really takes to do the skill. When you do a figure skating jumplanding, you always land on a toe
and then rock back to the heel.That toe impact is not where the highest impacts are. Youget a pretty high impact there. Then you rock back to the heel, and that's where you get up to 5 to 8 times body weight. That happensreally quickly. It's within 50 to 125 milliseconds. Comparing that torunning where you land with maybe two to three times your body weight in each step you take, we can see that thesemagnitudes are really high. The skating route provides very littleprotection.
In general, coaches and skaters may nottalk about landing forces all that often. It's just kind of a necessary evil. Thisis what happens. You know you land a jump, and you have these high magnitude forces. U.S. figure skating is really interested in this research because they want to be able to keep skaters healthy. They want to be able to keep their elite skaters performing at ahigh level, and then keep skating safe as a sport for any participant.
Science of the Winter Olympics Figure Skating
â™ªmusicâ™ª LESTER HOLT, Anchor: Every four years, we watch the stakes for Olympic figure skaters get higher, as they try to increase rotation in the air with their triple axels and quadruple toe loops. How do they do thaté It's a scientific principle that we asked Olympic hopeful Rachael Flatt and Deborah King, a sports scientist funded by the National Science Foundation, to help explain.
â™ªmusicâ™ª HOLT: Figure skaters make it look so easy: leaping off the ice, rotating through the air, and landing in a graceful arc. But make no mistake about it: figure skating is one of the most demanding of all the events at the Winter Olympics. For 17yearold Rachael Flatt, the demands of training for the Olympics have to compete with other demands. RACHAEL FLATT, U.S Figure Skating Team: I basically head to the rink
at around six o'clock. I ice skate from six thirty to seven fifteen. And then, um, I go to school from seven thirty until about twelve thirty. And then, um, basically from there I go straight back to the rink. HOLT: When she's on the ice, this AP Physics student might want to consider the science that goes into her every jump. To see this science in detail, Rachael agreed to train in front of a special highspeed camera called the Phantom Cam.
It has the astonishing ability to capture her jumps at rates of up to 1500 frames per second. RACHAEL FLATT: It's very cool watching myself on the phantom camera. You get to see every phase of the jump. And it's pretty incredible just to be able to see every aspect of it, you know, where exactly the placement of your arm is, and where my head is, you know, uh, just everything is really cool. HOLT: We brought the footage to Deb King,
a Professor of Sports Science at Ithaca College, and an advisor to United States Figure Skating. DR. DEBORAH KING, Ithaca College: A figure skating jump is a really complicated skill that combines a lot of different motions in it. They need to really optimize a lot of different conditions in terms of speed, force, vertical velocity, um, generating angular momentum, and put it all together in a packagewith just the right timingto execute the skill. HOLT: Deb watched the Phantom Cam footage to explain what Rachael
needs to get height and speed in one of her jumps. The first factor is Angular Momentum. DEBORAH KING: In figure skating, angular momentum determines how fast you are going to be able to rotate in a jump in the air. So when you do a spin, if you generate more angular momentum, you have the potential to spin faster. HOLT: Going into her jump, Rachael generates angular momentum by pushing off the ice with her foot.